The present invention relates generally to method and apparatus for compressing images and transmitting them, and particularly to a noticeable-image displaying method and apparatus that can display only images to be paid attention to, such as changing images, and to a system for remotely monitoring such images.
In the remotely monitoring system, the need for the apparatus that digitizes images and transmits them is now fast being increased because transmission lines have been rapidly digitized as represented by the Internet. Since digitization of images will greatly increase the amount of information, an image compression technique is absolutely required. The compression systems necessary for video images here are almost global standards such as MPEG-2 and MPEG-4. These systems basically aim to precisely compress the input images to transmission systems, and they are the technology for minimizing the deterioration of image quality due to the compression.
In the image monitoring system, the observer pays attention to chiefly the changed region of the shot images that are used for observation. For example, the changed region can be seen in the cases of checking for unwanted people to go into a prohibited area, and observing traffics such as flow of traffic, and movement of persons around a targeted region (an area where valuable goods are placed such as showroom in which people should not touch showpieces). Thus, the image monitoring system does not always need all regions of the image to be monitored that are to be compressed by MPEG-2 or MPEG-4.
This type of image monitoring system using the prior art for paying attention to the changed region of image is usually used to detect intruders by infrared sensors that are provided around the prohibited area, transmit the shot images of the prohibited area, and at the same time send the detected signals to the receiver side, thus alarming the observer (person who monitors the transmitted images).